This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 100 20 825.8, filed on Apr. 28, 2000, the entire disclosure of which is incorporated herein by reference.
The invention relates to a method and a device for closing a door, particularly of an aircraft. When a door is closed in a closed position, it is then also brought into a latched position, whereby the door is latched in the frame of the fuselage structure by a latch mechanism.
Conventional aircraft doors have at least one latch mechanism with a drive shaft drivable by a latch drive. The drive shaft is connected to a latch element arranged on a latch axis or shaft and to the latch drive. The latch element is adapted for engaging a latch stop arranged in the frame of the aircraft structure. German Patent Publication DE 197 02 084 C1 discloses such a door for an aircraft. The door is moved from an open position to a closed position and then to a latched position, with the door being latched in the frame of the fuselage structure by a latch mechanism.
It is further known to guide a door, during closing at the end of the swinging-in movement, along a stroke motion path which essentially conforms to the exterior contour of the aircraft. The stroke motion path is essentially aligned transversely to the swinging direction of the passenger door. At the end of the swinging path and at the start of the stroke motion path, the passenger door is lowered and guided into a closed position by a manual operation of a hand lever. The closed position involves a positive engagement of the stop elements which are fixed to the door, with the accommodating elements which are fixed to the door frame. At this stage the hand lever has not yet completed its entire travel path. There is still a small distance to be traversed by the hand lever. A further manual operation of the hand lever along the travel path until the limit position of the hand lever has been reached, latches the passenger door in the closed position by means of a door latch mechanism. The latch mechanism brings the door into a latched position and holds it there. The latch mechanism for a passenger door functions independently of a support device and of a tilt-position control of the passenger door. In the structurally simplest case the passenger door is latched by a bolt or a hook movable into a latching position, whereby the bolt engages an anchorage in the door frame of the aircraft structure, or the hook reaches behind a stop. The latch mechanism with the bolt or hook is for example activated by a rotatable drive shaft which is connected to the manually operable hand lever.
Aircraft which are in service today are equipped with doors which are manually swingable, by activating a hand lever, into the closed position and onward into the latched position. The force of the hand lever is transmitted to the latching axis or shaft with the bolt or hook through a drive shaft and a rod assembly.
Dynamic loads on the door during the f light can result in vibrations which may cause a reversal of the latch action. This can lead to the danger of the passenger door opening during flight. Such a danger might also exist if the latch drive breaks.
In view of the above it is an object of the invention to achieve the following objects singly or in combination:
to avoid door failures particularly during flight, and especially of the latch mechanism of an aircraft door;
to provide an economical door latching and locking mechanism useful for any door but particularly suitable for various types of aircraft doors;
to latch and safety lock a door, such as an aircraft door, with a single drive that is operable either by a hand lever or a motor, preferably moving in the same direction for all functions; and
to avoid using separate drives for the latching and safety locking functions.
The method according to the invention achieves the foregoing objects in that a latch mechanism which holds the door in a latched position is locked by means of a safety lock mechanism which due to a delayed movement of a respective force transmission coupling is activated by a single drive, whereby the latching and safety locking steps are performed in sequence by the same drive.
The above objects have been further achieved by an apparatus according to the invention in that a single drive shaft for a latching mechanism is also connected to a safety lock mechanism by a respective force transmission coupling. The safety lock mechanism is hingeably or slideably held on a lock axis.
Further, the safety lock mechanism is arranged so as to engage a lock element attached to a latch axis.
In the case of an existing latch mechanism, the latch drive is guided according to the invention along a remaining travel distance by means of a single drive for the latching and the locking, with a delayed movement of the safety locking mechanism into a safety locking position with a slightly spaced apart engagement with a lock element on the latch axis. The delayed movement is transferred to the lock element or elements from the single drive through a second force transmission coupling, with the latch drive or first force transmission coupling remaining in the latching position. The single drive and first and second couplings or force transmissions comprise for example a gear arrangement. Preferred, however are coupling rods and journal links. Gear wheels, cam disks or a cam controls are also suitable for realizing the first and second couplings. However, the use of rods and journal links with angular positions and dead points is particularly cost-effective. According to a special embodiment, these rods and links with angular positions and dead centers or points constitute the force transmission couplings between the single drive and the latching and safety locking mechanisms. An intermediate shaft can be arranged between the drive shaft and the lock drive or between the drive shaft and the latch drive. In this way, the movement mechanism can be optimized.
According to a further embodiment, the latch axis or shaft can be connected to a transmission mechanism which synchronizes latching and locking of a vent flap in the door, relative to the latch and lock mechanism of the door. Similarly, an indicator for showing the door status xe2x80x9cclosedxe2x80x9d,xe2x80x9clatchedxe2x80x9d and xe2x80x9csafety lockedxe2x80x9d may be coupled to the single drive. According to a further embodiment, the drive shaft can be connected to a transmission mechanism which guides the door from an open position to a closed position and vice versa.
The invention is suitable for use in doors other than aircraft passenger doors. Any closure that needs to be latched and locked can be equipped with the present apparatus. The term door is intended to include, e.g., any freight door, any cargo hatch closure, any closable engine fairing or any other closures that are not subject to pressure, in the secondary structure of an aircraft such as cabin doors and closures of passageways between decks. The term door further includes any closure cover which in its open position is not connected to the frame of a fuselage structure.
The invention provides the advantage that with only one drive, which already exists for the purpose of latching, the additional function of xe2x80x9csafety lockingxe2x80x9d is achieved, whereby savings are achieved by avoiding additional production costs and additional door weight. There is no increase in inspection expenditure.
Although the latching and following safety locking involves an additional operator function at the door, the operator comfort achieved by a single drive is maintained, particularly since any direction reversal of the drive between latching and safety locking is avoided according to the invention.